U.S. Pat. No. 6,297,197 B1 describes inter alia certain 6-(alkoxy or aryloxy)-4-amino-3-chloro-5-fluoropicolinate compounds and their use as herbicides. U.S. Pat. Nos. 6,784,137 B2 and 7,314,849 B2 describe inter alia certain 6-(aryl)-4-amino-3-chloro-5-fluoropicolinate compounds and their use as herbicides. U.S. Pat. No. 7,432,227 B2 describes inter alia certain 6-(alkyl)-4-amino-3-chloro-5-fluoropicolinate compounds and their use as herbicides. Each of these patents describes the manufacture of 4-amino-3-chloro-5-fluoropicolinate starting materials by fluorination of the corresponding 5-unsubstituted pyridines with 1-(chloromethyl)-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate). It would be advantageous to produce 4-amino-5-fluoro-3-halo-6-(substituted)picolinates without having to rely on direct fluorination of the 5-position of the pyridine ring with an expensive fluorinating agent like 1-(chloromethyl)-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate).
U.S. application Ser. No. 13/356,691 describes inter alia processes for the preparation of 4-amino-5-fluoro-3-halo-6-(substituted)picolinates comprising fluorinating a 5-chloropicolinate ester with a source of fluoride ion. U.S. application Ser. No. 13/356,686 describes inter alia processes for the preparation of 4-amino-5-fluoro-3-halo-6-(substituted)picolinates comprising fluorinating a 5-chloro-picolinonitrile compound with a source of fluoride ion. Due to the relatively weak electron withdrawing ability of the ester functional groups, highly reactive fluoride ion source such as CsF is preferred for the fluorination processes disclosed in U.S. application Ser. Nos. 13/356,691 and 13/356,686. When a less reactive fluoride ion source such as KF is used, the fluorination of chloropicolinate compounds may lead to low to moderate yield of the desired product due to incomplete fluorination and decomposition of the starting materials and products under forcing conditions. It would be advantageous to provide improved and more cost efficient methods for the preparation of 4-amino-5-fluoro-3-halo-6-(substituted)picolinates without having to rely on expensive chemical reagents such as CsF.